This paper represents the beginning of modern solar-terrestrial physics and one of the most important discoveries in astronomy.

''Schwabe was born on October 25, 1789, in the town of Dessau, near Berlin, Germany. He studied pharmacology in Berlin and then returned to Dessau in 1812 to assume management of his family's apothecary shop. While studying to become a pharmacist, Schwabe also become interested in astronomy ans soon immersed himself in various astronomical studies as a hobby.

In October 1825 he began his systematic observations of the Sun - a dedicated effort that extended for more than 17 years. His primary objective was to discover the planet Vulcan that some professional astronomers postulated resided close to the Sun inside the orbit of Mercury. While trying to catch a glimpse of this nonexistent planet as it traveled across the face of the Sun, Schwabe also noticed and sketched sunspots - thereby establishing a very careful record of their population and patterns as a function of time. He made very detailed sunspots records, but the sunspots themselves were of only secondary interest. Weather conditions permitting, he observed the Sun almost daily.

By 1843, however, his quest for Vulcan proved fruitless. At this point, inspiration struck Schwabe. As he reviewed almost 17 years of carefully recorded sunspot data, he suddenly noticed that there was an approximate 10-year (now established more precisely as 11 years) periodicity in the number of sunspots on the solar disk. Later that year, he announced this important astronomical observations in an article titled 'Solar Observations During 1843' that appeared in in the German journal Astronomische Nachrichten''. Deborah Todd - Joseph A. Angelo: Scientists in Space and Astronomy, 2005, p. 256

It is worth noting that Schwabe's observatory was a small room on the roof of his house.

''In 1857 Schwabe received a gold medal from the Royal Astronomical Society [Carrington, the famous British astronomer, took this medal to Dessau] and in 1868 he was elected a member of the Royal Society. Instead of the intramercurial planet he first sought, Schwabe instead found the 11-year, or Schwabe sunspot cycle. When receiving these awards, he said of his efforts: I can compare myself to Saul, who went out to find his father's asses and found a throne.'' Douglas V. Hoyt - Kenneth H. Schatten: The Role of the Sun in Climate Change, 1997, p. 35

Today (Cycle 24), the decrease of solar activity suggests that the Sun is on its way towards the Maunder Minimum of activity - as well as in the period from 1645 to 1715 - namely, we enter into another Little Ice Age. See:https://www.nature.com/articles/srep15689#f1